docs: def unweighed(self):
          """
              This method creates a *plain* (unweighted) copy of the internal
              formula. As a result, an object of class :class:`CNF` is returned.
              Every clause (both hard or soft) of the WCNF formula is copied to
              the ``clauses`` variable of the resulting plain formula, i.e. all
              weights are discarded.
  
              :return: an object of class :class:`CNF`.
  
              Example:
  
              .. code-block:: python
  
                  >>> from pysat.formula import WCNF
                  >>> wcnf = WCNF()
                  >>> wcnf.extend([[-3, 4], [5, 6]])
                  >>> wcnf.extend([[3], [-4], [-5], [-6]], weights=[1, 5, 3, 4])
                  >>>
                  >>> cnf = wcnf.unweighted()
                  >>> print cnf.clauses
                  [[-3, 4], [5, 6], [3], [-4], [-5], [-6]]
          """
  
          cnf = CNF()
  
          cnf.nv = self.nv
          cnf.clauses = copy.deepcopy(self.hard) + copy.deepcopy(self.soft)
          cnf.commends = self.comments[:]
  
          return cnf